The goal of this proposal is to generate funds to purchase a new EPICS Elite ESP flow cytometer. The user group in this application, all members of the University of Colorado Health Sciences Center newly formed Department of Immunology, includes the chairs of the Department of Immunology (KH) and the Rheumatology Division of the Department of Medicine (WPA) as well as the Executive Director (GSE) and the Research Director (RGG) of the Barbara Davis Center for Childhood Diabetes. The major user group also includes the PI's of training grants in Immunology (JCC), Rhematology (WPA). Pediatrics (ARH) and Diabetes (GSE). In total these training programs Support yearly the training of 13 post-doctoral fellows and 5 graduate students. The 10 major users are recipients at the time of the anticipated award of over 1.7 million dollars annually in direct NIH support. The new instrument will be located at the Barbara Davis Center for Childhood Diabetes at the Health Sciences Center. It will replace the existing instrument, an EPICS C that is 11 years old. The EPICS C will be replaced because it has antiquated data storage capabilities, an inefficient water cooled laser and is incapable of more than simple two color analyses. The new instrument, like the one that it is designated to replace, will be operated and managed using an existing structure in place at the Barbara Davis Center on the Health Sciences Center Campus. An advisory group including other users in the Health Sciences Center Department of Immunology, who are not situated at the Barbara Davis Center, will provide a balanced management policy for all major users. The purchase contract includes training fees to upgrade the technical expertise of the existing operator, who is presently an expert in operating and maintaining the EPICS C. User fees will be charged to fund management and maintenance of the instrument. Although projected usage should provide enough funding, operating costs not covered by these fees will be absorbed by the Barbara Davis Center with funds provided to the Executive Director, George S. Eisenbarth, who is also the Principal Investigator on this proposal.